The invention concerns a container or drinking cup the side sections of which form a cylinder and, more particularly , the same formed in one piece with a square or rectangular bottom which, in addition, serves as a base for the cup.
The structures mentioned heretofore shall be referred to hereinafter as a cup. A cup with a cylinder of four side sections may be formed with a rectangular folding bottom, as is generally known and for example described in U.S. Pat. No. 4,711,390. It enables the user to handle the cup in flat form when the cup is not in use. Two opposite sides of the cup's four side sections have folding lines which form the sides of isosceles triangles with base lines that in the open position of the cup, form two of the four edges at the bottom. At the bottom, parallel with the other two edges of the bottom, there is a folding line running along the centre line of the bottom and connecting the base lines of the two triangles. This folding line continues up along the perpendiculars of the two triangles, such that the two isosceles triangles are divided into two triangles with angles of 45.degree. each. The folding line continues on from the two triangles up to the rim of the cup, thus dividing the two opposite sides into pairwise congruent surfaces the insides of which can bear upon each other when the bottom is folded into the inside of the cup around the central folding line, whereby the insides of the other two side sections of the cup, which are parallel to the central folding line, are made to bear upon each other by parallel displacement of the latter two sides. Such a cup is primarily intended to contain liquid or frosted liquid and viscous or damp substances, for which reason the cup material is sealed, i.e. manufactured in a material or with an inside surface which is resistant to the contents of the cup. The cup is meant to be disposable after use, for which reason the material for the construction of the cup has a relatively short lifetime, such as vacuum-moulded or injection-moulded plastic, or cardboard or carton the inside surface of which may be protected by a waterproof material, such as pasted plastic film, wax or varnish.
The known cups of the type with the bottom specified above have four side sections connected to one another at right-angled corners, and the top contour of the cup forms a square opening unsuitable for use in drinking cups, which are usually shaped with circular or polygonal, ring-shaped openings, which both stabilize the shape of the cylinder and additionally form gutter-shaped or spout-shaped structures which collect the liquid in a controlled flow over the rim of the cup when the opening of the cup is tipped from a horizontal to an inclined position. Cups with four side sections as described above are therefore of another type than cups as specified in accordance with this invention, and such cups are often also designed with a closure at the top or with a lid which stabilizes the cylinder of the cup, so that the cup appears rigid and stable because the position of the sides relative to one another is fixed by the closure above. Cups of this type, with four side sections, are only mentioned here because such cups are designed with a folding bottom of a type which is also used for the invention specified here, of which the other modes of functioning are new, while the mode of functioning of the known folding bottom is used in a new way in this invention, for which reason the state of the art is represented by disposable drinking cups in a permanently open form.
The cups generally known are mainly manufactured in flexible materials such as thermoplastics or carton, for which reason various bends in the material are incorporated resulting in a certain rigidity in the sides, bottom and opening, intended to ensure that the contents of the cup do not unintentionally flow over the upper edges of the cup if the latter is subjected to external pressure which might otherwise deform it, whereby the contents would be pressed out over the top edges of the cup. The known cups are typically furnished with a circular opening above, reinforced with a folded bead all the way round, which provides good protection against the above-mentioned pressure. In practice no cups are known with a square opening above, inasmuch as external pressure in that case would have the result that the four right angles inside the square opening would be deformed such that two diagonally opposite angles in the square opening would become greater than 90.degree., while the other two angles would become less than 90.degree., whereby such a cup with liquid contents would be particularly unstable to handle, and would lack the necessary gutter-shaped or spout-shaped structure which a drinking cup must have. The cups generally known are given their final shape during manufacture. Many of these cups are therefore formed with a conical cylinder allowing the cups to be stored inside one another. Such cups may be manufactured in plastic or carton. Other cups of cardboard or carton are furnished with a cylinder which typically has three, four or more straight side sections. Such cups, which are intended to contain liquid, are furnished with a stabilizing closure above. No cups are thus known with a stable opening above, consisting of curved edges, and which are further designed with a folding bottom of the above-mentioned type. Drinking cups with a permanently open form further pose particular problems in use of an ergonomic, hygienic and aesthetic nature. These problems and the way of remedying them will be further described and related to the cup as specified in accordance with the invention.